Automatic thermostatic register



B. G. COPPING 2,523,499

AUTOMATIC THERMOSTATIC REGISTER Sept. 26, 1950 2 Sheets-Sheet 1 Filed May 8, 1948 BRUCE G. COPP/NG Sept. 26, 1950 B. e. COPPING 2,523,499

AUTOMATIC THERMOSTATIC REGISTER Filed May 8, 1948 2 Sheets-Sheet 2 I IIIIII/n TIIIIIIII/I/IIIIIIIIIII. II

2 ZZHYEHE:

15/21/05 6. COPP/NG h L'IIIIIIIIIIIIIIIII fiatented Sept. 26, 1950 AUTOMATIC THERMOSTATIC REGISTER Bruce G. Cupping, Atlanta, Ga assignor to Don Manufacturing Company, Chicago,

notation of Illinois 111., a cor- Application May 8, 1948, Serial No. 25,838

7 Claims.

This invention relates to an improvement in automatic registers and more particularly an automatic register'of the type intended for use in warm air home heating systems of the forced air type.

The present subject matter constitutes a continuation-in-part of that disclosed in, my copending application, Serial No. 708,224, filed November 7, 1946. 1 l g In one form of heating system, air, under pressureis applied to appropriate ducts-which lead to a plurality of rooms or spaces to beheatt ed. Each duct is provided with one or .more registers to control the quantity of air passing therefrom into the rooms. Theseregisters each comprise a frame defining an opening; leading from the appropriate duct to the room orspace and a shutter is interposed in this opening to control the quantity of air flow therethrough. The registers contain automatic elements. and operate in response to the temperature of the air in the room to open and close the shutter to control the quantity of air admitted thereto in such fashion as to maintain constant the temperature therein.

One requirement of an effective automatic register is that the position of the movable'shutter be varied in accord with the temperature of the room or spacebeing heated. To this endyit'is necessary to expose the thermostatic control element to a temperature representative of this temperature as distinguished from the temperature of the air entering the room. As the temperature of the air entering the room through the ducts influences the temperature of the thermostatic controlelement, the shutter will naturally tend to close and thereby defeat its own purpose.

A further requlsite'of an effective automatic register is that a sturdy structure capable of operating without deflecting or bending be provided so'that compensating movements which would defeat the movements of the temperature sensitive element do not and can not take place. This requirement is of particular importance Further, it is an object of the present invention to provide an improved automatic register suitable for use in heating homes.

Yet another object of the present invention is to provide an improved automatic register wherein the thermostatic control element partakes of the average air temperature in the room or space being heated.

Still another object of the present invention is to provide an improved aspirator structure for an automatic register. I

,It is yet another object of the present invention to provide an improved automatic register having a sturdy structure suitable for use with a control element having limited movement. 7 It is further an object of the present invention to provide an improved automatic register capable of being readily installed in a house or other structure. i p It is still another objectof the present invention to provide an: improved automatic. registerhaving features of construction, combination, and

- arrangement providing a unitary structure capawhere the control element'is of a type capable of only limited movement.

Still another requirement of an effective matic register for use in homes is that it be of simple "construction and reliable operation as well as being of low cost and, moreover,-thatthe autocomplete unit be adaptable for convenient mounting in a home. i

' It is therefore a general object of the present invention to provide an improved automatic register. 1

ble of effectively controlling the admission of air to a room or space.

Certain features of the ventilator herein described are described and claimed in my copend- .i'ng application, Serial No; 25,837 filed May 8,

1948, assigned to the same assigne-as the present invention. a

The novel features which I believe to be characteristic of my invention are- S'et forth with particularity in the appended claims. -My-invention, itself, however, both as to its organization and method of operation may best be understood byreference to the following description taken in connection with the accompanying drawings in which: i

Figure 1 is a front elevational view of an automatic register constructed in accordance with the present invention as it appears when mounted on a wall; v

Figure 2 is anfiend elevatlonal view of the register of Figure 1;

Figure 3 is a front elevational view of the register of Figure l with thecover plate removed; Figure 4 is a view of the register like Figure 3 but from below;

Figure 5 is a view of the register like Figure 3 but from the rear; 7 v i Figure 6 is an enlarged cross sectionalview through the axis VI-VI, Figure 3; I Figure 7 is a cross sectional view through the axis VII-VII, Figure 6; c

Figure 8 isa view like Figure 3 but from the Figure 19 isi-a cross sectional yiewlthrough the.

Figure 11 is a cross sectional View through the axis XL-XI, Figure 3.

Referring now to the frontsandcside,views-'of Figures 1 and 2, the register of the present invention comprises a housingfZfl having af-pair'of; spaced rectangular openings2'2 eachpfwhi'ch'is closed by a plurality of spaced louvers 24. As seen from the side, the housingwzllis oflrounded shape to define a pleasing appearance.

A temperature control, knob 26 extends from the end of thehousingZtland, as will be described inffiurther detail hereafterj'ma'y be adjusted --to control the flow of air "through the windows or openings 22 to accomplisn=any predetermined room'temperaturef This is achieve'd by aligning an indicator arrow- 21 with a' desired temperature k,25. .n 7 ii; 1. Y Thehousing is supported from a back-plate 28, Figure 3, bya plurality of:'-screws=-30. lI'he back-plate 28='has a centrallydisposed rectangular opening-3 2'; Figure 3,--which defines -a-pa's-sage in conjunction with theopenings- 22-,-Figure l, througlr which air from a duct '34,Figure;2, passes to-theroom or space to be 'hea'ted. 1

shown in -Figure 2; the'ihousinge20 is supported over theopenin of athesduct- -34 byany suitable means such as; for t. example, screws :extending through the. openings; in; the; backplate 28linto-a supportingwallsafiti he.

As is best shown in the views of Figures-13; 4 ands-9, aisupporti. plate c3 8=iiscmollnted 01.1.; one :end ottthe: baclcplate' 2 8:.in tregistrywithathe opening 32, ..this support, platehaving la; bo m la e the .backiplaten zfi; Atathenopposite,endpf the 1 length; of the shutter;;46. ,IA,

back plate 28, the end portionof. that ,platelis upturned.to -.form .thewf uppp b p te shaped .bafile1plate .4-2 ;is,-atta,ched to -the; support p te. by s' o po qns. gans fin chamberin conjunction with the support plate 40 through whichair may travel from the duct owthe pqsition assumed out regard tothe position of-theshutteror-the pressuredrop-across' the louvers '24 in the region overtheopening'tl I r The provision of"a' completelyseparate and independent air path from the duct 34' -to the roorn or space 'being heated provides a particularly effective method of maintainingthe inward airflow through --thefaspiratoriduct defined by the housing 53. As-will be evident to-those skilled in I the art, the louversi24. interpose a substantial resistance to the flow of air. from the duct 34 to lth moom or 'space being heated, andw consequently there is a substantially increased pressure in the region between the shutter 46 and the louvers 24 in the region directly over the opening 32. If the aspirator opens into this air this pressure tends to oppose the aspirator action and under normal conditions reverse air flow will occur Such reverse airj fi'owfivould follow the pathfromthe region between the shutter 46 and the louvers 24 through the aspirator passageways and into the room or space and thus would heat ,th'e controlelement 168 in accord with the duct air temperature rather than the room air temperature.

' In the'independent passageway defined by the balile plate 42,the*'area of louvers 24 through whichitheair .canxescape is large compared with the area of the ports through which air entersfrom "duct 34, thus the pressure drop through the louvers 24 is very slight and no back pressure is built up to force reverselair'flow through the housing 53k A red 44;='Figurer3,i- 42 and the support .plate:-38":bearing-at one end against the housing 53 to take up the pressure therebetween and: supplement the back :plate 28 inresisting-the .f0'rces associated with: operationof the'reg'i'ster. :1

A shutter 46, Figures 3 and 11, is.'po'sitioned across the opening-324 1. .This shutteris supported for. rotationaboutan' axis through; a rib;portion 46caby. a cord suspension-to bedescribed in further detail'lhereaftereu -;r

is best .shownsinl :Figureeljl, theqshutter .6 is made-up. ofitwotmetahsheetsieof L-shaped; cross section. andiridentifiedg asdlfi'aiand 1461), Figure 11. One leg of-each' obthese; sheetsisspot welded or otherwisetattached togtheg. corresponding leg of the otherlto defines-the. rib.- 45C. e en the ind w, 6 F ure 4, isprovided-rat one endtoi this rib and receives "the calibratinggmechanism shown gener-- ally: at 48. A; tab 50 isattachedto theopposite endof'therib46c; As will be described in further detail hereafter, the chamber definedL'by'the-bafiie.42 contains a temperaturecontrol assembly indicated generally iat= 5,2, This assemblytensions cord. 54, Figure'r', inaccord with.the ,temperature in the room; or: space. being heated; the amount ,of. this tension increasing the room air temperature falls.v v

The. tab .50 is-attachedwto acord suspension which operates to :sustain: the-shutter 46 e in position and .which,:.in,-addition, rotates. that shutter invaccordwithlthe-tensionpnlthe cord 54. ,As will be. evidentfrom. theegreatly enlarged fragmentary view of Figure 9, this suspensionincludes apairof cords 55,! and-58 which are anchoredat theinopposite ends to the-:supportplate 38 and the v@projectinggfinger portions ,50c; and 50d of tab.,=50, 'Ihe.-cords 55 and 53 are prefe rably.:ma .de ;of 2| stran d;-stain1es s; steel aircraft type'cable whien-hasarelativel sm ll op t to-bending andmtwisting Anchorstfl are press fittedv on the opposite ends ofjthe-cords 56 and bottomed against suitabielzopfinings in the -tab 50 s and the :supportplate 38; .t anchor the cords .56 land 58- in,-.DQSition. a :means of simplifyi the as mblytth n hqrs O a da j ent the su t ate .idebear a in suitable ope i sinauxi ia yesu or p et fi and support plate 38 is provided witnalengthy slot 38d in which the .asse nblypf au Xiliar-y plate 62 a qlz qrds; f endi5 may eins t h l 38d also defines an anchor for the reduced end portion of the bar 44, thus sustaining thatba'r extends between the 'ba fiie" pendicular to the shutter 46 by the auxiliary sup'g port plate 62 and are spaced in direction par-l allel to the shutter. 46 by the tab 58 which anchors these cords to that shutter. Consequently,

the cords 56 and 58 define a twisted plane and when these cords are tensioned,- they exert torque tending to rotate the shutter 46 in direction toalign the points of attachment of the cords 56 and 58 in a single plane. 1

Tension on the cords 56 and 58 is exerted seen in Figure 4, the tab 38a is located relatively close to the back plate 28 and the tab 38b is located a relatively further distance therefrom. I

The springs 66 and 68 are hooked to the extensions 58c and 58d of the tabs' 58a and 58b,r'e: spectively, of tab 58. in the direction of the axis of rotation of the shutter 46 as will be evident from Figure 9.

From the figures it will be evident that the springs 66 and 68 exert torque tending to rotate These extensions extend the shutter 46 in direction opposite the direction 6 of rotation associated withtorquecaused by tensioning the cords 56 and 58. Thus the springs 66 and 68 act to close the shutter 46 against the torque of cords 56 and 58 and to tend to hold the shutter in the closed position shown in Figure 3. r 1 The elements comprising the temperature control assembly 52, Figure 3, and the temperature control knob 26 are seen best in Figure 6, which is a, cross sectional view through the axis VIVI, Figure 3. The housing 53 is of die cast construction and is of generally cylindrical shape with a wall 53a in abutting relationship with the bafile plate 42. At the end opposite wall 53a, the interior of housing 53 is threaded as indicated at 53b and terminates in an annular lip 530 which surrounds the temperature adjusting knob 26 and has the arrow 21, Figure 3, formed at a, fixed point thereon. The temperature adjusting knob 26 is of molded plastic construction and at one end bears threads 26a which are received in threaded engagement by the threads 53b of the housing 53 to sustain the temperature control knob in position and to permit adjustment of the position thereofIAt the end opposite threads 26a, the temperature adjusting knob 26 terminates in a plurality of inwardly extending ribs 26b which may be seen in end view in Figure 8. These ribs engage the wall defined by the enlarged portion 68a of the temperature sensitive element I68 and terminate in radii corresponding to the radius ofthe re duced end portion I68b of that element. This forms a snug seat against which the element I68 bottoms.

ina wing portion having a plurality of radially extending ribs which engage the interior of the temperature control knob 26 to sustain the spacer 14 therein. The end 14a further has a recess 14b to receive the piston I680 of the temperature senstive element I68.

At an end opposite wing 14a, the spacer I4 has a cavity 140. Moreover, the cap I6 fits over the end of spacer I4 and about the cavity 140..

This cap is of drawn metal construction-and has a centrallydisposed opening through which the cord 54 passes. A tab 18 is press fitted on the end of cord 54 and bottoms against the cap 16 to hold that end of cord 54. The cavity 140 is ofsize freely to receive the tab I8. 5'

The edge portions 16a of a cap 16 are bent over to define an annular wall against which the small end of the compression spring 88 bottoms. The large end of this spring bottoms against the wall 53a of the housing 53 and thus urges the cap I8, the spacer I4, and the temperature sensitive element I68 against the ribs 26b of the temperature control" knob 26'. This action of spring 88 holds the elements within the housing 53 and the temperature controlknob 26 snugly in place and, moreover, tensions cord 54 in accord with the diiferential between the force exerted by the temperature sensitive element I68 and the compressive force of spring 88.

Temperature sensitive element I68 may be any one of various devices having a dimension varying in accord with temperature. Preferably this element is of the so-called Vernet type wherev in a change in volume of a material during its transformation from one physical state to another is utilized to effect change in dimension of the control element. It is, of course, a well known fact that a change in volume takes place in most materials upon change from a solid to a liquid state or from a liquid to a gaseous state.

These elements utilize such volume changes to efi'ect a change in a dimension thereof throughout a predetermined temperature range. In the specific type of Vernet element shown in the drawings, Figure 6, the piston I680 moves outward or to the left in Figure 6 with increasing temperature and inward with decreasing temperature. 1

The end of 'cord 54 opposite the end to which tab 18 is fitted is attached to the rib portion 460 of the shutter 46 by the calibrating assembly 48. This assembly includes a collar 82, Figure 6, of brass or similar material having a central opening to receive the cord 54 and which is slotted 'to receive the rib 460 of the shutter 46 in the portions adjacent the extended slot portion 46c of a window 46d. Tab 84 is press fitted to the end of cord 54 and bottoms against the end of the collar 82. The end of collar 82 adjacent the tab 84 is threaded and receives the nut 86 in threaded engagement. This nut bottoms against the edge of the window 46d to sustain the en- Open spaces 18,-Figure 8, are formed between the adjacent ribs 26b. These spaces define passages for air flow through the temperature adjusting knob 26 as indicated by the arrow 12, Figure 6.

The spacer 14 comprises a generally cylindricalrod of molded plastic material such as, for

example, Bakelite and. terminates at-end' 14a tire assembly, including collar 82, tab 84 and cord 54, in fixed relationship to the rib 460.

The back plate 28 has a pair of bent-up ta-b portions 9I, Figure '7, which define openings 98 are in the form of tabs which define openings= The tabs 91 and i92;r..togethertwith rthei open-v ings 90 and 94 define an' aspiratorvstructure whichcreatesva low pressure region-v adjacent= the open; ings 'i94tland draws fair'f through the housin 53 4, and the itemperature control knob '2 6 j-as indicated byiithe arrow lz; Figure-6m It iwill bBOb'I-e" 1" serve'di' that' the upturned. portions =.of tabs: 91 guide' the airidirectly past'fthe tabs 92 inua mane".- ner most favorable to :production' of 'high: velocity? 'an'd ai lowipressure area behind -the =ta'bs a92 and adjacent windows '94.-- .This1ow:pressure-area:-1 r

effectively; draws-air through: .th'e"' knb '26 and causes 'Jthe1temperature -:control elements I68 toa partake i of-u the average 1 airs-temperature in": the r room ori'spaceabeing; heated as distinguished from:

theftemperatt'ire'of'the air inthedu'ctidz 2o Theaoper'atiorr of the-registeriof the present in Y ventionnwillbe 'apparent fromfrtheforegoingde scriptionfi Air? underrpressurei':in duct=34 Figure; 2, tr'aivelsl'throu'ghrthe:openingsM-dntmthe *cham ber idefine'diby :the bafiie 4 2; and thereby." induces-t 53 r.

aid-currents". fo1lowing ;thearrow: 1 2; through the.

temperature'sadjusting sknob'r2fi and the; housingr 53:1 These air icurrentscause --thew temperature-- sensitive e1ement I tsrto partake ofthe average' airtemperature in the" roon'1- ror space being heated? .Ifrthisnir temperature 'f'alls below= the a temperature at -which-l thQ'FknOb +26 isw set, the: temperature sensitive "element: I68 experiences 5 reduced -lengthiy thereby causingthe entire: as-

semblyrincluding spacer 14; ca 6 .-andthe "end of.:spring;.8fl to extend inrthe right-hand direc-w. tidrniFigure 16h This tensions :thecord 54-and-im+ parts icorre'spondingvtension tothe cords '56 (and: 58; thereby impartingqtorque to the shutter- 46oand causing the latterto rotate f=in-directionto 40 permit-more: air flow from th'e -duct. 34=-thr0ugh the openings 32,-: :Figure: 3w This opening. oper ation' will continue :until; theposition ofmthe shut-1; ter- 46i's .su'chr'zthat the heat carried by theaair enteringcthe roo'm isiequai toithe heatilost there home-thereby;attaining-the temperatureidesiredfi The: function 1 of the calibratingv, assembly .48; r

is to fix the position of the shutter 46 at'aHpreH- selected postion of the temperature-control: knob 26 'Thei latter includes a series of temperature: 50

numbersi'25for 'registryfwith the pointer :21 which is 'formedziniheihousing 53.:v It is; of :course; sub-r stan'ti'a'lly;impossible' to manufacture ar precision. instrument such. .as a the I register of the; presentinvention in massprod'uction without encounter-- ing substantial: variations between 'indi vidu'alunits insofar as the temperaturecalibration isrr concerned. To-attempt to overcome this .probelm by. the'uuse of more accuratetsprings 80;:662and:

I68 together with closer dimensional tolerances oo is i uneconomic'alnandw would increase :the costots. the: vunitxbeyondrthe justifiable cost:v

The calibrating assemble 5' 48 overcomes lth isi 5 problem fonv'the :niut 186 3 may; be adj ustecl v-relative predetermined position, the shutter? 46 is heldt. in an'zintermedi'ate position" when the element. 68 is? at the" temperature corresponding to the;- settirigofthe-knob 26-." When thisz-adjustmenthasfb'een madea drop-of cement-,ma-y be placed on zthe' portion of the nut .86 adjacent the collar 82-sto prevent 'loss of calibration due to accidental-l rotatiorrof the nut.86: 7 7

:The amountofmoti'on of thepiston-lfiac of-rthe'.

temperature: sensitive-element" I68 per degree of tempi'aturichangfe fis: affected-ibyqvariations. in F the pressure against whichthe-pistonis workings, Ifith'e reactingspressure increases astherpiston moves outward" to the left; thenthez amount of v travelperidegreer; of temperature change is. IGSSG-IIQdIL Conversely; ifs the piston moves 1 out against aidecreasing resistance, then. the .amount of trave1 perrdegree of 5. temperature change is: incr'easeds As thettemperaturefalls; the-reacting spring;- press'urerforc'es thei-pistorr back. If this-return" ing pressure": decreasesizas; the :piston backs :in, then the amount of backward motionper:degree; of temperature dropais lessened. If; on. the other hand, \th'ee returning; pressure increases.- as: the piston backs up, then theamountof backward motion-Lperr degrees of temperature; drop "is in..- creased... Thus,:for-maximum motion of ;the.-.piston} both'i'outward .1 and: inward; the pressures; against the r piston is Working should-.1 be l 192513 1111 theaoutward sposition and :greatestinzth e;

iI'lWQITdSrpOSitiOIIZi I v Th'easpringsrtfi and 68 exert a.--torque:on= they shutter 1'46 ,eandithroughwthez actionzot the cords. 56* and? 58 this torque istranslated into tension; on-the cord 54;: which tension opposes'the force ofg the springRMiwLTIius, the net pressure againstzthe. piston 1| 68cris the-pressure of the-springaBDuminus; 1 the tensiorr'son the cord 54 resulting; fromwthe torquelofthezsprings:66'and.' 68:

Byiisuitable arrangement: of: the angularity ot. the tabs:50csandv50d;,.the;torque exerted :-by;;the; springs Gfi a-n'diGBe may.-.be;made to decrease as. the. shutter: opens. to' such an extent that the; naturalincreaseiof -forcezirrth'e springqflflvzis mores than offset; andlthe desired. reduction of reactinga'; pressure as the: piston; moves: out. is: obtained..; v This operation is described in detail in my copendingvpatent' application, Serial- No.. 25,835? filedlIMay 8; .1948; assignedto the same: assigneee as theipresents invention:

Byprovidingetheerod 44", Figure;3, the supp rt.- plate 38 g and; hence the anchors ;of: cords 56 andw 58 are. held.- against:. shifting movement relative to the backiiwa'lti53ur of l the housing 53 'againstwhich the spring.v B0 bottoms. Inasmuch as; a-,: subst'antialltensioning force; must be. exerted: by; the cordir54 to; overcome; :the; bias of. springs-- 6 it ands; there; is asubstantial compressiveforce exerted: on? the: back: plate; Z8 a;force.; that in herently tends to buckle thatwp late and shift the; support plate 38 to defeat the purpose. achieved by. theishifting movement of spacer member: 14;. Rodsdeovercomes these effects without requiring. heavier construction. of the. back plate. 28:: and,- without; interfering. with! the: operation of the. controlr elementsaor: the rotation of: the shutter.. Moreover; the rod 44- extends' substantially. be tweenthe'ipoints of: application of the 'tensioning force'ssandz accordingly acts in I the most. efficient? manneninisupplementing the action of the. back.

plate 28.

Therba'ck plate: 28z'isnpr0vid6dfWith a plurality of mounting openin szlflll; I02; l03'and HM; Fjg--= ure:5 together with a pair. ofiangle bracketsJflB-u andc lflas These; coacthto enable convenient; mounting of the shutter in either a four-:inch; afive -inoh;,or aesix; inch;duct; Ductsofthese dimensions are; standard inbuilding construc.-- tion; and the provision of these openings. permits: EDQHOQHOHqOfithB register ina manner that would otherwise require a great number of frame sizes. and would correspondingly. increase theexpense thereof Whemtheregister-is used with afive or six inch -duct, the brackets I 06 and I08]- are g rotated as: shown in F figure fiend-the mounting screw is inserted through the opening I04 which leaves ample room for the six inch duct and suitably centers the opening BZ-reIatiVe-tothe duct. On the other hand, when a four inch duct is encountered-the brackets lfl fifand I 08"are rotated l80 "to the position shown in the dotted linesof ,Figure 5, thereby causing the opening 32 mm aligned with the duct when the brackets I06 and I08 are bottomed against the edge of the duct. The opening I02 may be used to fasten the shutter in position in the four inch duct.

Rubber grommets or inserts may be provided to close the unused openings I00, I02 or I04.

The foregoing universal mounting is achieved by spacing the centers of rotation of the brackets I06 a distance of approximately two and threeeighths inches from the center of the opening 32 and by positioning the upstanding portions of these brackets approximately one-fourth inch from the centers of rotation.

In actual automatic thermostatically controlled shutter built in accordance with the principles of the present invention the marks 25 are spaced approximately three-eighths of an inch and represent 2 F. difference in room temperature. This variation in room temperature corresponds to approximately 0.014 inch of travel of the member 14 and corresponding movements of the cord 54. This movement is sufficient to rotate the shutter 46 through an angle of approximately 45 and moves the tip of the shutter blade approximately an inch and one-half. Thus an original motion of .014 inch is converted into actual shutter opening motion of one and one-half inches or one hundred times as much motion as the thermostatically controlled element itself is capable of making. This tremendous step up in motion, achieved without substantial frictional losses, accounts for the unusual effectiveness of the shutter of the present invention. Moreover, to get a similar multiplication of motion without back lash and lost motion would require precision machinery increasing the cost of the register to a prohibitive value. While I have shown a particular embodiment of my invention, it will, of course, be understood that I do not wish to be limited thereto since many modifications both in the elements employed and their cooperative structure may be made without departing from the spirit and scope of my invention. I, of course, contemplate by the appended claims to cover all such modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In an air flow controller, a duct through which air is carried into a room, a shutter for controlling the flow of air from the duct into the room, a grille outside the shutter which impedes such air flow, a thermostat for controlling the position of the shutter, a tube around the thermostat and having an air inlet independent of the duct in communication with the room at mosphere and an aspirating passage behind the grille and isolated from the duct, said passage communicating with said tube and carrying a limited high-velocity, low-pressure flowof air from the duct to draw air from the room through said tube over the thermostat.

2. A temperature conditioning air flow appa-- ratus of the type including a thermostatically controlled damper structure in control of air flow through a duct carrying temperature conditioned fluid comprising, a thermostat directly adjacent the ducttc'; Eontrol the positionof the damper in the duct, a fluid. chamberto oneside ,of the, damper having a restrictedopening to the U rate.aspirate: passage along thethermostat and having'one end communicatingfwith'.the atmosphere outside of the duct and'having the 'other end communicating with said fluid chamber, whereby the higher velocity fluid flowing through said chamber will induce a flow of atmospheric fluid through said passageway about the thermostat.

3. In an air flow control apparatus of the type including a duct with a thermostatically operated shutter at the end thereof for controlling the fiow of air to a room, the improvement of a frame at the end of the duct and bafiie elements projecting from the frame and together therewith forming a flow passage independent of the main duct outlet into the room, said flow passage having a restricted duct inlet and a proportionally greater room outlet, whereby air at duct pressures will pass through said duct inlet and through said flow passage at increased velocity and reduced pressure, and an open ended casing for the thermostatic control elements, said casing having one end thereof communicating with said flow passage and having the other end thereof communicating with said room, whereby air from the room will be aspirated through the casing into the flow passage for exposing the thermostatic control elements to room temperature.

4. An air flow control apparatus according to claim 3 wherein the frame is a flat plate-like element having a main air flow aperture and having an opening adjacent thereto forming the flow passage duct inlet and the bafile elements are arranged on the flat plate-like element relative to said flow passage inlet opening to form the independent flow passage isolated from the main air flow through the duct into the room.

5. An air flow control apparatus according to claim 4 and further characterized by the provision of a grille extending substantially across the register and disposed in front of the main air flow aperture and the independent flow passage.

6. In an air flow control apparatus of the type including a duct which has a thermostaticallyoperated, shutter-controlled register at the end thereof for controlling the flow of air into a room, the improvement of an aspirator structure for exposing the thermostatic control elements to room temperature comprising a register frame, means carried thereby and defining therewith an independent flow passage, said flow passage having a restricted duct inlet and a proportionally greater room outlet whereby air at duct pressure will pass through said duct inlet to produce a high-Velocity, low-pressure flow of air in the fiow passage and a housing for the thermostatic control element communicating with the flow passage and with the room whereby air from the room may be aspirated through the housing into the flow passage for the purposes set forth.

7. In a register structure including a frame and a damper for regulating flow of duct fluid through the same, an adjustable thermostat connected to said damper for actuating it in response to room temperature changes, said thermostat being on the exterior of the register frame in a manually accessible position, means defining an 7 

